石窟围岩地震变形破坏机制的数值模拟分析
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摘要
针对石窟文物的特点,阐述了影响石窟围岩变形稳定性的主要因素和动力有限元分析方法。以敦煌莫高窟的2个典型工段为实例,通过对不同峰值加速度、频谱、持续时间的动荷载作用下石窟围岩位移场、应力场分布特征的数值模拟计算,揭示了岩土体及其附属构筑物在地震作用下的动态响应和变化规律,指出了窟体防护加固的重点部位。分析结果表明,随着地震动峰值加速度(PGA)、反应谱特征周期和地震动持续时间的增大,洞窟的位移和应力值明显增大,应力集中区的范围扩大,围岩损伤的可能性增加,稳定性降低。应力分布与洞窟数量、组合特性、几何形状和尺寸密切相关,并控制了石窟围岩的震害特征。其成果为石窟文物的科学保护和岩体抗震加固与减灾提供理论基础和实践依据。
Considering characteristics of Grotto Relics,the influence factors and dynamic finite element analysis methods on deformation stability grotto country rock are discussed.Focusing on two sections of Mogao Grottoes in Dunhuang of Gansu Province,the dynamic response and variation regularity of rock mass and its adjuncts are revealed through numerical simulation of displacement and stress field under dynamic loads with different PGA,spectra and durations.The results indicate weak points for seismic retrofitting.It also shows that the displacement and stress increase,range of stress concentration expands and the damages probability of country rock increases with the increase of peak ground acceleration(PGA),characteristic period and duration of dynamic loads.The distribution of stress is closely related to the quantity,combination feature,geometry shape and size of caves.This paper provides theoretical basis and practical reference for the preservation of grotto relics and seismic retrofit and seismic hazard mitigation for the rock mass.
Considering characteristics of Grotto Relics,the influence factors and dynamic finite element analysis methods on deformation stability grotto country rock are discussed.Focusing on two sections of Mogao Grottoes in Dunhuang of Gansu Province,the dynamic response and variation regularity of rock mass and its adjuncts are revealed through numerical simulation of displacement and stress field under dynamic loads with different PGA,spectra and durations.The results indicate weak points for seismic retrofitting.It also shows that the displacement and stress increase,range of stress concentration expands and the damages probability of country rock increases with the increase of peak ground acceleration(PGA),characteristic period and duration of dynamic loads.The distribution of stress is closely related to the quantity,combination feature,geometry shape and size of caves.This paper provides theoretical basis and practical reference for the preservation of grotto relics and seismic retrofit and seismic hazard mitigation for the rock mass.
引文
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[4]陈卫忠,朱维申,王宝林,等.节理岩体中洞室围岩大变形数值模拟及模型试验研究[J].岩石力学与工程学报,1998,17(3):223-229.CHEN Wei-zhong,ZHU Wei-shen,WANG Bao-lin,et al.Numerical simulation and testing study of large deformation for cavern’s surrounding jointed rockmass[J].Chinese Journal of Rock Mechanics and Engineering,1998,17(3):223-229.
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[7]石玉成,徐晖平,王旭东.敦煌莫高窟地震安全性评价[J].敦煌研究,2000,63(1):49-55.
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